1. Field of the Invention
This invention relates to a recording apparatus which records an image on a recording medium.
2. Related Background Art
A recording apparatus such as a printer, copying machine and facsimile device is so constructed that an image consisting of a dot pattern is recorded on a recording sheet such as paper and a thin plastic sheet by driving an energy generating unit for a recording head in accordance with image information to be transmitted.
As an example of the recording apparatus, an ink jet recording apparatus is described below.
The ink jet recording apparatus used as a recording apparatus provides very low noise during recording and a high-density multidischarge port is easily provided, and therefore it is capable of recording at a high speed. Since color reproduction of a color image is also easy, it has been drawing a large degree of attention recently.
Among the other recording methods, a method to discharge ink droplet by utilizing heat energy is capable of providing the highest density among all recording methods because a flow path can be formed by using a thin film technique, and accordingly, this is suitable for high-speed recording.
An example of the recording head used for such an ink jet recording apparatus, is a so-called full line type recording head in which plural discharge ports have been formed over the entire recording width of the recording sheet.
These plural discharge ports lead to a common liquid chamber within the recording head respectively, and this common liquid chamber is connected to plural (for example, two) ink feed pipes, which are connected to an ink tank in which ink to be fed into the recording head is stored. They are so constructed that ink is fed through both ink feed pipes during recording, and ink flows in one direction in the following order the ink tank, one ink feed pipe,: the recording head, other the ink feed pipe and the ink tank again, when the recording head performs a recovery operation.
The ink quality of the image recorded by jet recording head is likely to deteriorate because improper ink discharge occurs owing to evaporation and drying of ink, dirt due to ink leakage, adhesion of dust, or the occurrence of an air bubble in the ink feed path, etc. To prevent this improper discharge, it is necessary to carry out the recovery operation, etc. of the recording head, which is performed by idle charging ink through all discharge ports of the recording head during recording or during non-recording, and by allowing ink to flow in one direction as mentioned above.
Also it is necessary to seal the discharge ports while the recording head is not used, and for that purpose, capping means should be provided. Therefore, the recording head should be moved from a position where it should be during recording.
On the other hand, the ink jet recording apparatus discharges and causes ink droplet to fly through the discharge port of the recording head by utilizing heat energy to allow the ink droplet to adhere to the recording sheet for recording as mentioned above. Therefore it is necessary to maintain an interval, minute and constant, between the recording head discharge port and the recording sheet in the discharge direction. The interval between a recording position of the recording head and the conveyance path of the recording sheet should be precisely stabilized.
Also, on the other hand, the above-mentioned ink jet recording method is designed to discharge and to cause the ink droplet to fly through the discharge port of the recording head and to allow the ink droplet to adhere to the recording sheet for recording. Therefore it is necessary to maintain an interval, minute and constant, between the recording head discharge port and a surface through which the recording sheet passes in the discharge direction.
According to a conventional configuration, a platen guide is allowed to abut on a platen roller so that the recording line of the recording sheet is brought just behind the platen guide terminal. Since, however, the recording sheet is put on a bent sheet path, when recording is performed after a lapse of time, a recording sheet tends to take on the shape of the sheet path, causing sheet conveyance and exhaust sheet problems after recording. The tendency of the sheet to take on the shape of the bent sheet path is not corrected after recording, but becomes inconvenient in appearance and arrangement.